This patent application relates generally to electrical connectors that may be configured to carry high frequency signals.
Electrical connectors are used in many electronic systems. It is generally easier and more cost effective to manufacture a system as separate electronic assemblies, such as printed circuit boards (“PCBs”), which may be joined together with electrical connectors. A known arrangement for joining several printed circuit boards within a single enclosure is to have one printed circuit board serve as a backplane. Other printed circuit boards, called “daughterboards” or “daughtercards,” may be connected through the backplane. Connectors designed for this connecting daughtercards and backplanes are widely used.
Some electronic systems are assembled with electronic components in different enclosures. Those enclosures may be connected with cables, which may be optical fiber cables but more commonly contain electrically conducting wires for conveying electrical signals. To facilitate easy assembly of the system, the cables may be terminated with cable connectors, sometimes called plugs. The plug is designed to mate with a corresponding connector, sometimes called a receptacle connector, attached to a printed circuit board inside an enclosure of an electronic device. A receptacle connector may have one or more ports that are designed to be exposed in a panel of the enclosure. Typically, a plug can be inserted into each port.
To facilitate manufacture of different portions of electronic system in different places by different companies, aspects of the receptacle connectors and the plug connectors may be standardized, either through a formal standard setting process or through adoption of a particular design by a large number of manufacturers. An example of a standard is referred to as SAS. As another example, several such standards exist as a result and are referred generally to “small form factor pluggable” (SFP) connectors. Variations of these standards exist under names such as SFP, QSFP, QSFP+, etc.
Different standards have been developed as electronic systems generally have gotten smaller, faster, and functionally more complex. The different standards allow for different combinations of speed and density within a connector system.
For standards that require a high density, high speed connector, techniques may be used reduce interference between conductive elements within the connectors, and to otherwise provide desirable electrical properties. One such technique involves the use of shield members between or around adjacent signal conductors. The shields may prevent signals carried on one conductive element from creating “crosstalk” on another conductive element. The shield may also impact the impedance of each conductive element, which may further contribute to desirable electrical properties of the connector system.
Another technique that may be used to control the performance of a connector entails transmitting signals differentially. Differential signals are carried on a pair of conducting paths, called a “differential pair.” The voltage difference between the conductive paths represents the signal. In general, a differential pair is designed with preferential coupling between the conducting paths of the pair. For example, the two conducting paths of a differential pair may be arranged to run closer to each other than to adjacent signal paths in the connector.
Amphenol Corporation also pioneered the use of “lossy” material in connectors to improve performance, particularly of high speed, high density connectors.